This shot was processed entirely in Lightroom 2.5 (no photoshop trickery going on here!). You can see here the effect quite well, the sky is nice and dark, while the trees are a bit brighter than they would otherwise be. If you compare closely to the image below you can see the difference quite well. The general contrast is also much stronger.
This is the same shot, but taken without an IR filter, just converted to greyscale in Lightroom.
And here is the IR shot in colour (with corrected White Balance and Exposure in Lightroom 2.5). This is what was coverted to greyscale to get the IR image above.